Coupled anthropogenic anomalies of radionuclides and major elements in estuarine sediments |
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Authors: | Machado W Luiz-Silva W Sanders C J Patchineelam S R |
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Institution: | Departamento de Geoquímica, Universidade Federal Fluminense, Niterói, RJ, Brazil. wmachado@geoq.uff.br |
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Abstract: | Concentrations of fertilizer industry-derived P (up to 3.4%), Ca (up to 6.1%), (226)Ra (up to 744 Bq kg(-1)) and (210)Pb (up to 1317 Bq kg(-1)) at least one order of magnitude above natural levels were recorded in a sediment core from Morr?o River estuary (SE Brazil). Unsupported (210)Pb (= total (210)Pb-(226)Ra) activities unexplained by atmospheric fallout and deviations from the radionuclides secular equilibrium also indicated strong anomalies. Anomalous constituents were positively correlated with each other and negatively correlated with clay mineral-bearing elements. These negative correlations were explained by a depletion of natural sediment constituents due to a dilution caused by elevated inputs of steel industry-derived elements (mainly by Fe levels up to 24%). Absolute data and normalizations by a proxy for clays (Al) and anthropogenic Fe evidenced variabilities in the quality of coastal and land-derived sediment inputs, mainly due to changes in the relative contributions from industrial sources. |
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